Semiconductor processing in the fabrication of integrated circuitry typically includes the deposition of layers on semiconductor substrates. Exemplary processes include physical vapor deposition (PVD), and chemical vapor deposition (CVD) which herein includes atomic layer deposition (ALD). With typical ALD, successive mono-atomic layers are adsorbed to a substrate and/or reacted with the outer layer on the substrate, typically by successive feeding of different precursors to the substrate surface.
Chemical vapor depositions can be conducted within chambers or reactors which retain a single substrate upon a wafer holder or susceptor. Typically, depositions are conducted at subatmospheric pressure. The chambers are maintained at subatmospheric pressure by one or more vacuum exhaust lines extending therefrom and through which undeposited effluent material flows. In certain chemical vapor deposition processes, for example in ALD, a deposition precursor might be pulsed to the chamber. When the flow of such precursor is not occurring to the chamber, the precursor might be diverted to flow directly to the exhaust line and thereby by-pass the deposition chamber. Further in certain of these and other processes, another deposition precursor might be continuously flowed to the chamber while an intermittent precursor is pulsed between the chamber and the exhaust line. These and other processings can result in considerable deposition of product within the exhaust line(s). If allowed to build up, this can lead to less vacuum pressure, and eventually result in nearly complete occluding of the exhaust line. Exemplary prior art methods for contending with the cleaning of the exhaust line include the complete removal and cleaning of the exhaust line from the deposition equipment, thereby undesirably providing considerable downtime for the equipment. Alternately, a cleaning fluid jacket is provided along the internal exhaust line surfaces, with the cleaning fluid flowing during the deposition of product onto substrates within the chamber to avoid any deposition in the first place.
The invention was motivated in addressing or overcoming the above-described drawbacks, although it is in no way so limited. The invention is only limited by the accompanying claims as literally worded without interpretative or other limiting reference to the specification or drawings, and in accordance with the doctrine of equivalents.